It has been the case for many years that the most optimal way to handle defunct pages on your website was to have the server return a 404 (Not found) HTTP status code. Google has just recently confirmed, however, that they now consider the 410 (Gone) response code to be a stronger signal that the page has gone away for good.
HTTP response codes are designed for both users and search engine spiders to give them information about what has happened to a site’s page. When a user stumbles upon a page that is issuing a 404 or 410 response code, they will sometimes see the message “Page Not Found”. So, if both of these response codes yield the same response for the user, what is the benefit of using one over the other?
According to Google, when a page issues a 404 header response, it may sometimes still revisit the page to ensure that it is truly defunct. What this means in terms of indexing is anyone’s guess, but using the 410 response code will at least ensure that Google will never go back to that page again and get to the more important pages on the website, thus facilitating crawlability.
The 410 response code should be used when there is no other option, meaning that this page cannot be redirected to a similar or corresponding page. So if you’re absolutely sure that a page no longer exists and will never exist again, using a 410 would likely be a good thing. It’s probably not worth the time or effort rewriting a server by changing the 404 to a 410, but using the 410 in the future will at least give Google the stronger message that they are looking for.